Modulation by copper of the products of nitrite respiration in Pseudomonas perfectomarinus

Abstract

A synthetic growth medium was purified with the chelator 1,5-diphenylthiocarbazone to study the effects of copper on partial reactions and product formation of nitrite respiration in Pseudomonas petfecmto1nar-inlus. This organism grew anaerobically in a copper-deficient medium with nitrate or nitrite as the terminal electron acceptor. Copper-deficient cells had high activity for reduction of nitrate, nitrite, and nitric oxide, but little activity for nitrous oxide reduction. High rates of nitrous oxide reduction were observed only in cells grown on a copper-sufficient (1 F.M) medium. Copper-deficient cells converted nitrate or nitrite initially to nitrous oxide instead of dinitrogen, the normal end product of nitrite respiration in this organism. In agreement with this was the finding that anaerobic growth of P. perfectomarinus with nitrous oxide as the terminal electron acceptor required copper. This requirement was not satisfied by substitution of molybdenum, zinc, nickel, cobalt, or manganese for copper. Reconstitution of nitrous oxide reduction in copper-deficient cells was rapid on addition of a small amount of copper, even though protein synthesis was inhibited. The results indicate an involvement of copper protein(s) in the last step of nitrite respiration in P. pe:fectomnarinus. In addition we found that nitric oxide, a presumed intermediate of nitrite respiration, inhibited nitrous oxide reduction.

Potential role of copper availability in nitrous oxide accumulation in a temperate lake

“…Cu speciation and N 2 O accumulation-Lab culture studies clearly show that N 2 O accumulates during denitrification at low Cu concentrations. Such an effect has been demonstrated previously (Iwasaki and Terai 1982;Matsubara et al 1982;Granger and Ward 2003), but these earlier studies only compared Cu-replete and Cu-depleted conditions, providing little quantitative information about the Cu speciation conditions where Cu limitation is first observed. Using one of the same species as Granger and Ward (2003), we found N 2 O accumulation to increase at total dissolved Cu concentrations of 1 nmol L 21 , corresponding to a total inorganic Cu concentration of 0.6 fmol L 21 .…”

“…The enzyme that catalyzes the reduction of N 2 O to N 2 , nitrous oxide reductase, contains four Cu atoms per molecule (Zumft 1997), imparting on denitrifying bacteria an obligate requirement for Cu. Laboratory studies with several strains of denitrifying bacteria have shown that N 2 O accumulates in Cu-limited cultures of denitrifying bacteria (Iwasaki and Terai 1982) and that these denitrifiers cannot utilize N 2 O in the absence of Cu (Matsubara et al 1982). More recently, Granger and Ward (2003) estimated the concentration of inorganic copper species that would limit full utilization of N 2 O by marine denitrifiers.…”

The impact of copper, nitrate and carbon status on the emission of nitrous oxide by two species of bacteria with biochemically distinct denitrification pathways

“…NosZ is located in the bacterial periplasm and has a unique multi-copper-sulfide centre (Cu4S2), called CuZ, that is capable of binding and activating N2O prior to its two-electron reduction using electrons delivered by a di-nuclear Cu centre called CuA (Pomowski et al, 2011). Synthesis of NosZ therefore potentially places a high demand on the bacterium for an adequate supply of Cu from its environment (Matsubara et al, 1982;Minagawa and Zumft, 1988;Granger and Ward, 2003;Moffett et al, 2012). The electron donors to P. denitrificans NosZ in vivo are the haem-Fe cytochrome c550 and the Cu-containing pseudoazurin.…”

Molybdopterin guanine dinucleotide is the organic moiety of the molybdenum cofactor in respiratory nitrate reductase from Pseudomonas stutzeri

“…Bacterial strain, growth conditions and enzyme preparation P. stutzeri strain Zobell (ATCC 14405) was grown anaerobically in a synthetic asparagine-, citrate-, and nitrate-containing medium [16]. Growth conditions, cell rupture, and isolation of respiratory nitrate reductase followed the published procedure [15].…”